Knives are usually comprised of a handle with a blade that is interconnected thereto. Some knives employ blades that are rotatably interconnected, and selectively lockable, to the handle. When the knife is not in use, it is sheathed or, in the case of folding knives, the blade is folded into the handle. When in use, the rotatable blade is extended from the handle and locked in place. Such locking mechanisms are known and engage a portion of the blade to hold it in place until the user disengages the lock mechanism, which allows the blade to be folded into an opening in the handle to conceal all or a portion of the blade.
Regardless of knife type, it is desirable to provide a cutting edge that is very sharp, similar to the sharpness provided by a razor blade. However, razor blade sharpness comes at a price. More specifically, razor blades often possess very thin edges that are brittle and wear, i.e., lose their edge, relatively quickly. Blade performance can be repaired by sharpening, but doing so will reduce blade size and durability. In addition, thin razor blades lack lateral strength and are thus flimsy and can fracture easily when put to hard use to cut forcibly or when cutting at an angle that applies lateral side-force to the blade. Thus, some knives employ a razor-sharp replaceable blade element that fits within a blade carrier, which may be foldable within a handle. Once the replaceable blade element becomes dull, or after repeated sharpening, it is removed from the blade carrier and discarded. Another razor blade is then inserted into the carrier.
Some knives of this type employ a complicated blade interconnection mechanism. For example, U.S. Pat. Nos. 5,689,889 and 6,574,868 to Overholt disclose razor blades for interconnecting to a blade carrier of folding knife. These knives receive the replacement blade member in a complicated fashion wherein the replaceable blade element must be first introduced into the blade carrier at and angle and then rotated into place. Finally, the replaceable blade element is locked within the blade carrier. As one of skill in the art will appreciate, replacing a blade in this fashion is difficult and, because the replaceable blade members are extremely sharp, manipulating the blade into place can cause injury. To lock and secure the blade, Overholt discloses the use of a separate threaded fastener that attaches to the blade carrier. To replace the blade, the fastener must first be loosened and completely detached from the blade carrier before the sharpened razor blade portion can be removed. This is time consuming and dangerous because the user must remove the fastener by hand from the blade carrier, which is located in close proximity to the sharp cutting edge of the razor blade. Further, loosening or removing the fastener requires the use of both hands, which makes it not possible to safely hold the knife or secure the knife by the handle while removing the fastener. Further, the fastener is commonly made up of two or more small parts that must be detached from the blade carrier to replace the blade. The fastener parts can easily be dropped and lost, especially when used in the outdoors. If one or more small parts of the fastener are lost when changing the blade, the new blade cannot be attached to the blade carrier and the knife is no longer functional.
The following disclosure describes a knife with the replaceable blade that is selectively inserted into blade carrier in a way that facilitates easy interconnection, reduces the chance of injury, and eliminates the need for separate parts that must be detached from the knife to remove and insert a new blade.